An ultrahigh vacuum, magnetron sputtering system for the growth and analysis of nitride superlattices

An ultrahigh vacuum, magnetron sputtering system designed for the deposition and in situ analysis of nitride superlattices is described. Superlattices are deposited from two sputter sources aimed at a fixed substrate position. The chamber features a sample insertion load lock, a computer-controlled shutter to modulate the sputtered fluxes, a retarding field analyzer for in situ low energy electron diffraction and Auger electron spectroscopy (AES), and substrate heating to > 800 °C. Deposition of epitaxial TiN, VN, NbN, and nitride superlattices is described. Deposition rates decreased, and the film nitrogen content increased until stoichiometry was reached, as the N2 partial pressure was increased. The film thickness and composition were uniform to within 10% over the 1.2 cm wide substrates. AES studies of the initial stages of TiN deposition onto VN(100) indicated a layer-by-layer growth mechanism. Single-crystal TiN/NbN(100) and TiN/V0.6Nb0.4N(100) superlattices were grown and found to have flat, sharp interfaces, and exhibited hardness enhancements in excess of 200% over homogeneous alloys of the same composition.